Patient's comfort is an important objective in modern dentistry. The delivery of cold fluid, such as water, into a patient's mouth during treatment can be very discomforting when the patient's teeth and gums are sensitive to sudden changes in temperature. It is a particular problem when, during the performance of certain surgical operations such as a root canal, exposed tissues in nerve endings are washed with cold water.
It is therefore desirable to preheat the water
it is delivered into the patient's mouth. However, the water must not be too hot or similar undesirable effects will result. A near body temperature of the water is preferred.
Conventional water heaters for use with dental equipment are sometimes provided with a large storage container in which water is stored after it has been heated electrically. The size of the heater usually precludes mounting near the dental instruments. When water is demanded of a remotely located heater, the room temperature water in the tubing must first pass through the dental instrument before the heated water reaches the instrument. Hence, the temperature of the water at the point of use is difficult to control.
Some remote heater systems use a drip line which allows a small volume of water to constantly flow from the heater, up to the dental instrument and out through a drain. Although this system maintains warm water at the instrument, it uses a large amount of water, and a drain line must be provided.
In the prior art, rapid water heaters have been developed to heat water immediately prior to its use. Typically, these heaters are based on complicated and expensive baffle systems or thermostat designs where thermostats are submerged into the water to be heated. A thermostat based on the temperature of the water sometimes over lags the water temperature and control of the water temperature is erratic. Other water heaters include heating devices and thermostats designed into the handle of a dental syringe. One shortcoming of this design approach is that the handle is large and heavy. Many dentists supply water to the instruments from an air pressurized water bottle, rather than a municipal water supply. However, if the bottle runs dry, overheating can occur because the thermostats of many conventional heaters do not function properly in dry conditions.